Aerobic exercise shows considerable promise as an intervention nurses and other health care professionals can recommend for HIV infected adults, with recent studies linking structured aerobic exercise training to improved physical, psychological, and immune system outcomes. Research remains preliminary, however, and further exploration of the effects of aerobic exercise training on HIV disease progression and symptoms is needed prior to developing guidelines for health promotion/health maintenance programs. This study examines the effects of a 12 week aerobic exercise training protocol on physical symptoms; immune markers; psychological depression; mood states; and aerobic power in HIV infected adults (CD4 200-499) without CDC-defined AIDS. This study is structured as an experimental study (two group, pre-test control group design) with the exercise group (n=30) to aerobically exercise 1 hour, 3 times per week, for 12 consecutive weeks. The control group (n=30) is to maintain usual activities, monitored by bi-weekly telephone or clinic contract. Subjects will be recruited through The Ohio State University (OSU) AIDS Clinical Trials Unit (ACTU) and will be main- streamed with The OSU Cardiac Rehabilitation and Faculty/Staff fitness program for the exercise protocol. Dependent variables of physical symptoms (energy imbalance/fatigue, dyspnea, and weight loss/body composition), immune markers (immune system cell counts and delated-type hypersensitivity (DTH) testing, psychological depression, mood states, and aerobic power (oxygen uptake, VO2- MAX) will be measured at baseline (pre-test) and at 12 weeks (post-test), with descriptive follow-up of subject outcomes continuing at 24 and 48 weeks. Data for pre-test to 12 weeks (post-test) will be analyzed using ANCOVA with pre-Test values entered as a covariate. Confounding effects of anti-retroviral medications are controlled through pre-randomization stratification; other potential confounders will be monitored and controlled as appropriate. This study will supply important data on effects of aerobic exercise on symptoms experienced by HIV infected adults with mid-stage disease (CD4 200-499) and will provide empirically based guidelines for use by nurses in designing health promotion/maintenance programs for this population.